Conversion of hydrocarbonaceous black oils

ABSTRACT

Hydrocarbonaceous black oils are converted into lower-boiling hydrocarbons via a process which utilizes two separate catalytic reactor systems interconnected by way of a multiple-stage separation facility. Fresh feed charge stock is reacted in the first reactor system in admixture with hydrogen recovered from the second reactor system. Conversely, unconverted material from the first reactor system is reacted in the second system with make-up hydrogen and all the recycle hydrogen recovered from both reactor systems.

APPLICABILITY OF INVENTION

As herein described, the process encompassed by my inventive concept isespecially adaptable for the mixed-phase conversion of aheavier-than-gasoline hydrocarbonaceous feedstock. More specifically,the present invention involves the use of two individual catalyticreactor systems which are interconnected by a novel, multiple-stagefacility for separating the mixed-phase reaction product effluent. In abroad interpretation, the process, hereinafter described in detail, isapplicable to hydrocarbon conversion which may be classified ashydrogen-consuming, and in which the various processing techniquesdictate the recycle of a hydrogen-rich gaseous phase. Suchhydrogen-consuming processes include the hydrorefining, or hydrotreatingof kerosene fractions, middle-distillate fractions, light and heavyvacuum gas oils, light and heavy cycle stocks, etc., for the primarypurpose of reducing the concentration of various contaminatinginfluences therein. Another typical hydrogen-consuming process is knownin the petroleum refining art as "hydrocracking". Basically,hydrocracking techniques are employed to convert relatively heavyhydrocarbonaceous material into lower-boiling hydrocarbon productsincluding gasoline, kerosene and fuel oil.

Relatively recent developments in the area of petroleum technology haveindicated that the hydrocracking reactions can be applied successfullyto residual stocks, or the so-called "black oils". Exemplary of suchmaterial are atmospheric tower bottoms products, vacuum tower bottomsproducts (vacuum residuum), crude residuum, topped crude oils, crudeoils extracted from tar sands, etc. Black oils are generallycharacterized by a boiling range indicating that 10.0% or more, byvolume, boils above a temperature of about 1050° F. (565.6° C.).Although the amount is not known accurately, a significant quantity ofblack oils currently exist which are characterized in that more thanabout 50.0% by volume boils above a temperature of about 1050° F.(565.6° C.). One specific example of a black oil is a vacuum residuumhaving a gravity of 8.8° API, and containing 3.0% by weight of sulfurand 4300 ppm. of nitrogen, and having a 20.0% volumetric distillationpoint of 1055° F. (568.3° C.). As hereinafter indicated by specificexample and by the embodiment presented for illustrative purposes in theaccompanying drawing, the utilization of the present process affordsadvantages when utilized for the conversion of such black oils. It willbe noted, however, that the foregoing brief description of petroleumprocesses utilize hydrocarbonaceous charge stocks boiling above thegasoline boiling range--i.e. having an initial boiling point above about400° F. (204.4° C.).

OBJECTS AND EMBODIMENTS

A principal object of the present invention is to provide aneconomically feasible catalytic process for the desulfurization andconversion of black oils into distillable hydrocarbons of lowermolecular weight and boiling range. A corollary objective is to providean integrated separation technique which effects a decrease in hydrogenloss while effecting the conversion of hydrocarbonaceous black oils.

Another object of the present invention is to provide an improved blackoil conversion process utilizing an improved separation technique forseparating the mixed-phase reaction product effluent, which producteffluent contains hydrogen, normally liquid hydrocarbons and normallygaseous hydrocarbons.

These and other objects are achieved by the present invention as morecompletely described hereinbelow, especially with reference to theaccompanying drawing which is a simplified representation of severalembodiments.

In a broad embodiment, the present invention directs itself toward aprocess for the conversion of a black oil charge stock, of which atleast 10.0% by volume boils above about 1050° F. (565.6° C.), whichprocess comprises the sequential steps of: (a) reacting said chargestock and hydrogen, in a first catalytic reactor system, at atemperature above about 700° F. (371.1° C.) and a pressure greater thanabout 1000 psig. (69.1 atm.); (b) separating the resulting firstreaction product effluent, in a first separation zone, undersubstantially the same pressure and a temperature not substantiallyexceeding 750° F. (398.9° C.), to provide a first vaporous phase and afirst liquid phase; (c) cooling said first vaporous phase to atemperature in the range of 50° F. (10° C.) to about 150° F. (65.6° C.),and separating the cool vaporous phase, in a second separation zone atsubstantially the same pressure as said first separation zone, toprovide (i) a hydrogen-rich second vaporous phase and, (ii) amethane-containing second liquid phase; (d) increasing the temperatureof said second liquid phase, and separating the heated liquid phase, ina third separation zone at a substantially reduced pressure, saidtemperature and pressure being selected to provide (i) a third liquidphase and, (ii) a third vaporous phase containing at least about 70.0%of the methane contained in said second liquid phase; (e) admixing afirst portion of said third liquid phase with said first vaporous phaseand a second portion with said first reaction product effluent; (f)separating said first liquid phase at substantially the sametemperature, in a fourth separation zone under a substantially reducedpressure below about 1000 psig. (69.07 atm.), to provide (i) a fourthliquid phase and, (ii) a fourth vaporous phase; and, (g) furtherreacting said fourth liquid phase with hydrogen in a second catalyticreactor system at an increased pressure above about 1000 psig. (69.07atm.).

In another embodiment, at least a portion of the second vaporous phaseis heated to a temperature above about 700° F. (371.1° C.), andintroduced into said second catalytic reactor system.

In a specific embodiment, the second liquid phase is heated to atemperature in the range of about 250° F. (121.1° C.) to about 500° F.(260° C.), and said third separation zone is maintained under a pressurein the range of about 200 psig. (14.61 atm.) to about 450 psig. (31.63atm.).

These, as well as other objects and embodiments, will become evidentfrom the following more detailed description of the present black oilconversion process and the separation technique integrated therein. Inone such other embodiment, the product effluent from the secondcatalytic reactor system is separated, in a fifth separation zone, atsubstantially the same pressure and at a temperature not substantiallyexceeding 800° F. (426.7° C.), to provide (i) a fifth vaporous phaseand, (ii) a fifth liquid phase, at least a portion of said fifthvaporous phase being admixed with said charge stock and introducedtherewith into said first catalytic reactor system.

CITATION OF RELEVANT PRIOR ART

It must be recognized and acknowledged that the prior art is repletewith techniques for effecting black oil conversion and separation of themixed-phase reaction product effluent. A perusal of the prior artClasses 208-59, 208-93, 208-101 and 208-102 indicates that such is thecase. The five delineated references discussed below are appropriate tothe present black oil conversion process; therefore, copies thereofaccompany this application.

In U.S. Pat. No. 3,364,134 (Cl. 208-93), issued to R. J. J. Hamblin onJan. 16, 1968, a black oil conversion process is described whichinvolves four separation zones (one of which initially separates thefresh feed charge stock) and two reaction vessels. The invention isstated as encompassing a method whereby the asphaltic material in thecharge stock is maintained in a dispersed state within a liquid phasewhich is rich in hydrogen. The fresh feed charge stock is initiallyseparated in the first separation zone (atmospheric flash column) toprovide a light fraction having an end boiling point of 650° F. (343.3°C.) to about 850° F. (454.4° C.), and a heavy fraction having an initialboiling point above about 650° F. (343.3° C.).

The heavy fraction is admixed with make-up and all the recycledhydrogen, and reacted in a first reaction zone, the effluent from whichis introduced into a hot separator functioning at a temperature of about700° F. (371.1° C.) to about 750° F. (398.9° C.) and at substantiallythe same pressure. Hot separator liquid is introduced into a hot flashseparation zone at a substantially reduced pressure below about 100psig. (7.81 atm.) and at a temperature of about 550° F. (287.8° C.) toabout 900° F. (482.2° C.). Hot flash liquid is withdrawn from theprocess as residuum while the hot flash vapors are admixed with the hotseparator vapors and the atmospheric flash light fraction, and reactedin the second reaction zone. Product effluent from the second reactionzone is introduced into a cold separator at substantially the samepressure and at a temperature of about 60° F. (15.6° C.) to about 130°F. (54.4° C.). A hydrogen-rich vaporous phase is withdrawn from the coldseparator and recycled to the first reaction zone; the cold separatorliquid phase is recovered as the product of the process. With respect tothe foregoing described process, it will be noted that there is norecognition of flash separating the cold separator liquid phase at anelevated temperature in a warm flash separation zone. Certainly,therefore, there exists no disclosure relative to the decrease inhydrogen loss. Additionally, the disclosed use of the two reactorsystems is contrary to the present process in that the effluent from thesecond system is introduced into a cold separator.

A hot separator, cold separator and hot flash zone are utilized inconjunction with a vacuum column in U.S. Pat. No. 3,371,030 (Cl.208-102), issued to J. R. Penisten et al. on Feb. 27, 1978. Reactionproduct effluent is introduced into the hot separator, the vaporousphase from which is condensed and introduced into the cold separator;hot separator liquid is introduced into the hot flash zone below a meshblanket contained therein. The hot flash zone functions at a temperaturesubstantially the same as the hot separator, but at a reduced pressurebelow about 200 psig. (14.61 atm.). This vessel serves to concentratethe 400° F.-plus (204.4° C.) hydrocarbons in a liquid phase which is inturn introduced into the vacuum column. A portion of the recovered heavyvacuum gas oil is reintroduced into the hot flash zone above the meshblanket, functioning as a wash oil. Cold separator liquid is admixedwith hot flash vapors and recovered as the product of the process.

The process described in U.S. Pat. No. 3,375,189 (Cl. 208-59), issued toR. J. J. Hamblin on Mar. 26, 1978, is similar to that of U.S. Pat. No.3,364,134 summarized above. Here, the hot separator vapors and the hotflash vapors from a first reaction zone effluent are combined andreacted in a second reaction zone. The effluent from the latter isintroduced into a cold separator, the hydrogen-rich vapors from whichare recycled to the first reaction zone. Cold separator liquidcomponents are fractionated to provide a 400° F.-plus (204.4° C.)fraction which is reacted in a third reaction zone, from which theproduct effluent is introduced into a second cold separator. The liquidphase from the latter is fractionated in admixture with the liquid phasefrom the first cold separator.

U.S. Pat. No. 3,402,122 (Cl. 208-101), issued to B. L. Atwater et al. onSept. 17, 1968, discloses a separation technique for recovering anabsorption medium from a black oil reaction product effluent. Utilizedare a hot separator, a cold separator, a hot flash zone and a cold flashzone. Salient features include recovering the absorption medium fromcondensed hot flash vapors and also introducing cold flash liquid intothe cold separator. Again, there exists no recognition of increasing thetemperature of the cold separator liquid and introducing it into a warmflash zone.

A somewhat similar separation technique is presented in U.S. Pat. No.3,371,029 (Cl. 208-102), issued to J. N. Weiland to Feb. 27, 1968.Again, four separation zones are involved: a hot separator, hot flash,cold separator and cold flash. Hot separator vapors are condensed andintroduced into the cold separator, while the hot separator liquid phasepasses into the hot flash zone. Hot flash zone vapors are condensed,admixed with the cold separator liquid phase and introduced into thecold flash zone at a temperature of about 105° F. (40.6° C.) and apressure below about 200 psig. (14.61 atm.). A portion of the cold flashliquid phase is recycled to the cold separator; the remainder beingadmixed with the hot flash liquid phase and subjected to fractionationfor desired product recovery.

From the foregoing description of the prior art techniques, it becomesreadily apparent that the prior art is not cognizant of the inventiveconcept described herein. Although some of these illustrative processesutilize multiple-stage product effluent separation integrated into a tworeactor system black oil process, none employ the technique of reactingthe fresh feed in a first system, in admixture with hydrogen recoveredfrom the second system, and reacting unconverted material from the firstsystem in the second system, with make-up hydrogen and all the recyclehydrogen recovered from both reactor systems. Furthermore, none employthe technique of increasing the temperature of the cold separator liquidphase and introducing the same into a warm flash zone at a pressureabove about 200 psig. (14.61 atm.). Therefore, such prior processescannot offer a reduction in hydrogen solution loss as afforded by thepresent inventive concept.

SUMMARY OF INVENTION

From the foregoing brief description, it will be readily ascertained, bythose possessing the requisite skill in the petroleum refining art, thatthe present black oil conversion process makes use of a unique tworeactor system flow scheme which is interconnected by a series ofintegrated steps for the separation of the mixed-phase reaction producteffluent. Although primarily intended for black oil conversion, it willbe recognized that the present process and separation technique areequally applicable to heavier-than-gasoline feedstocks which are notconsidered to fall within the black oil designation. In furtherdescribing the present invention and the process encompassed thereby, anillustrative conversion of a hydrocarbonaceous black oil will beutilized. Black oil conversion is intended to accomplished two primaryobjects: first, to effect desulfurization of the feedstock to the extentdictated by the desired end product, whether maximizing fuel oil,kerosene or gasoline boiling range hydrocarbons; secondly, it isintended to maximize the yield of "distillable hydrocarbons", beingthose normally liquid hydrocarbons having normal boiling points below1050° F. (565.6° C.).

Conversion conditions are those which are imposed upon one or morereaction vessels for the purpose of achieving both desulfurization andthe production of lower-boiling hydrocarbon products. Precise conditionsfor a given unit depend primarily upon (1) the physical and chemicalcharacteristics of the charge stock, and, (2) the character of theintended product slate. The process and separation technique does notdepend for viability upon the operating conditions utilized in thecatalytic reaction zones; those which are employed in the prior artprocesses hereinabove delineated continue to be suitable. For the mostpart, it will be noted that these conversion conditions aresignificantly less severe than those being currently commercially used;distinct economic advantages will be recognized. Briefly, the conversionconditions include temperatures above about 700° F. (371.1° C.), with anupper limit of about 800° F. (426.7° C.), as measured at the inlet tothe fixed-bed of catalyst particles disposed within the reaction zone.Since the bulk of the reactions being effected are exothermic in nature,the effluent from the reaction zone will exhibit a higher temperature.In order that catalyst stability be preserved, it is preferred tocontrol the exothermicity of reaction to the extent that the producteffluent temperature does not exceed about 900° F. (482.2° C.). Hydrogenis admixed with the black oil charge stock, by way of compressive means,in an amount generally not exceeding about 10,000 standard cubic feet ofgas per barrel of said charge stock, at the selected operating pressure;hydrogen is present in the recycled vaporous phase in an amount of about80.0% by volume, or more. Preferably, the quantity of hydrogen will bein the range of about 3,000 to about 6,000 standard cubic feet perbarrel. Black oil conversion requires superatmospheric pressuresgenerally exceeding about 1,000 psig. (69.07 atm.), and usually in therange of about 1500 psig. (103.1 atm.) to about 3000 psig. (205.2 atm.).The black oil is introduced into the reaction vessel at a liquid hourlyspace velocity (defined as volumes of liquid hydrocarbon charge per hourper volume of catalyst disposed within the reaction zone) of from about0.25 to about 2.0.

As hereinbefore stated, the present black oil conversion process employstwo separated catalytic reactor systems. Preferably for large units, asillustrated in the accompanying drawings, each system comprises a pairof parallel reactors; particularly preferred is the configurationwherein each of the parallel reactors contains at least two individualcatalytic reaction zones. Black oil units are seldom designed for acharge rate less than 50,000 Bbl/day, and the indicated preference forreactor systems facilitates control of the exothermicity of reactionsuch that catalyst activity and stability are preserved. Furthermore,the utilization of two reaction zones in each of the parallel reactorspermits the introduction of a liquid or vaporous quench streamtherebetween. Fresh charge stock, in admixture with a hydrogen-richvaporous phase, is introduced into the first catalytic reactor system,with approximately 50.0% of the total going to each of the two parallelreactors. The hydrogen-rich stream is the vaporous phase recovered froma hot separator into which the product effluent from the secondcatalytic reactor system is introduced.

Since the physical and/or chemical characteristics of the catalyticcomposite forms no essential feature of my invention, there exists nonecessity for a lengthy description herein. Suffice to state that aplethora of suitable hydrocracking/desulfurization catalysts aredisclosed in the literature, some of which are discussed in the priorart hereinbefore delineated. Briefly, however, such catalysts arecomposites of one or more metallic components from the metals of GroupsVI and VIII, combined with a refractory inorganic oxide, eitherzeolitic, or amorphous--e.g. a combination of alumina and silica. Forthis type of service, the catalytic composites are generally reduced andsulfided prior to use.

Reaction product effluent is introduced into a first hot separator atsubstantially the same pressure and at a temperature not substantiallyexceeding 750° F. (398.9° C.). Since this reaction product effluent wasderived from the fresh black oil charge stock, the first hot separatorfunctions above 700° F. (371.1° C.) to prevent ammonium compounds frombeing withdrawn with the liquid phase, and below 750° F. (398.9° C.) tokeep heavier material out of the vaporous phase. In most black oilconversion units, the effluent from the reaction zone will be at a levelexceeding 750° F. (398.9° C.), and hence must be cooled; this may beaccomplished by using a portion of the warm flash zone liquid phase, asshown in the accompanying drawing and as hereinafter described. Thevaporous phase from the hot separator is admixed with a second portionof warm flash zone liquid, condensed and introduced into a coldseparator at substantially the same pressure and a temperature of from50° F. (10° C.) to about 150° F. (65.6° C.). The liquid phase from thehot separator passes into a hot flash zone at substantially the sametemperature, but at a substantially reduced pressure of from about 100psig. (7.81 atm.) to about 400 psig. (28.23 atm.).

In the present specification and the appended claims, the term"substantially the same pressure" is intended to connote that nointentional actions are taken either to decrease, or increase the streampressure between one vessel and another; obviously, there will be a dropin pressure due to fluid flow through the system. Similarly, the phrase"substantially the same temperature" indicates that a given stream isneither intentionally heated, nor cooled when passing from one vessel toanother. Thus, hot flash zone liquid components will be raised inpressure prior to being introduced into the second catalytic system,whereas the pressure of the vaporous phase will decrease somewhat onlyas a result of flow through the system.

Cold separator liquid phase components are introduced into aheat-exchanger, in which they are indirectly contacted with a hotterprocess stream, to raise the temperature to a level in the range ofabout 250° F. (121.1° C.) to about 500° F. (260° C.). The thus-heatedliquid phase passes into the warm flash zone at a substantially reducedpressure of from 200 psig. (14.61 atm.) to about 450 psig. (31.63 atm.).Warm flash zone vapors are sent to suitable fractionation facilities forthe recovery of various product streams. As above stated, a portion ofthe warm flash zone liquid phase is combined with the first catalyticreactor system effluent to quench the same to a temperature below about750° F. (398.9° C.), and a second portion serves as a hydrogenenrichment fluid by being combined with the first hot separator vaporousphase prior to condensation and introduction into the cold separator. Toillustrate the use of this warm flash zone with the cold flash zone ofthe prior art, a basis of 50,000 Bbl/day fresh feed will be used. Usingthe cold flash zone at a pressure of about 50 psig. (4.40 atm.) and atemperature of about 125° F. (51.7° C.), the hydrogen solution loss isabout 114.8 scf/Bbl. Utilization of the warm flash zone, in accordancewith the present process, at a pressure of 300 psig. (21.42 atm.) and atemperature of about 363° F. (183.9° C.), the solution loss dropsmarkedly to 102.5 scf/Bbl., or 12.0%. The difference of 12.3 scf/Bbl.,assuming an average current hydrogen cost of $2.50/1000 scf., is about$1,535.00/day. Since most petroleum refinery processing units functionfor about 330 days per year, the annual savings in hydrogen costsexceeds $500,000.00.

The liquid phase from the first hot flash zone, containing primarily theheavier components and unreacted 1050° F.-plus (565.6° C.) material inthe effluent from the first catalytic reactor system effluent, serves asthe charge stock to the second catalytic reactor system. The pressurethereof is increased and a heated hydrogen-rich recycle stream isadmixed therewith. Since the hot flash zone liquid is obtained at atemperature approximating 745° F. (396.1° C.), there is no need tointroduce it into the direct-fired heater which raises the temperatureof the recycled hydrogen, the source of which is hereafter set forth.The reaction product effluent from the second catalytic system isintroduced into a second hot separator. In most situations, the effluentwill not require quenching; the pressure imposed upon the second reactorsystem will generally be about 150 psig. (11.21 atm.) to about 200 psig.(14.61 atm.) higher than that imposed upon the first reactor system.Therefore, the second system product effluent will be introduced intothe second hot separator at temperatures up to about 850° F. (454.4°C.); hot separator pressure is substantially the same as the secondsystem outlet pressure.

The vaporous phase from the second hot separator, concentrated inhydrogen, is admixed with the fresh black oil charge stock prior topassing the same into the direct-fired heater and into the firstcatalytic reactor system. Hot separator liquid phase components areintroduced into a second hot flash zone at substantially the sametemperature and a pressure in the range of about 100 psig. (7.81 atm.)to about 400 psig. (22.23 atm.), the same range under which the firsthot flash zone functions. Hot flash liquid phase components, containingthe unreacted 1050° F.-plus (565.6° C.) material, is sent to afractionation facility for product stream recovery. Vaporous phasecomponents from the second hot flash zone are combined with the vaporousphase from the first hot flash zone, the mixture being condensed at atemperature in the range of about 50° F. (10° C.) to about 150° F.(65.6° C.) and introduced into a compressor suction drum, or knock-outpot.

Normally liquid material is withdrawn as a bottoms stream for separationin a fractionation facility for product stream recovery. Thehydrogen-rich gaseous phase is admixed with the required quantity ofmake-up hydrogen, compensating for that consumed chemically in theoverall process, the mixture being introduced into a compressor whichincreases the pressure to the extent required to permit the same to becombined with the hydrogen-rich vaporous phase recovered from theaforementioned high-pressure cold separator. Hydrogen sulfide is removedfrom the combined stream, for example in an absorber utilizingdiethanolamine as the absorbent. The hydrogen sulfide-depleted hydrogenrecycle is again increased in pressure, passed into a seconddirect-fired heater and admixed with the liquid phase from the first hotflash zone.

BRIEF DESCRIPTION OF DRAWING

In further describing the present invention and the hydrocarbonconversion process encompassed thereby, reference will be made to theaccompanying drawing which is illustrative of the several embodimentsthereof. The drawing is presented by way of a relatively simplifiedschematic flow diagram in which only the principal vessels are shown.Reduced in number, or completely eliminated are details such as pumpsand compressors, heaters, coolers and condensers, heat-exchangers,start-up lines and heat recovery circuits, fractionation columns,valving, instrumentation and other controls; they are not believedrequired for a clear understanding of the techniques involved.Utilization of such miscellaneous appurtenances, to modify theillustrated process, is well within the purview of one possessing areasonable degree of skill in the petroleum refining art, and will notremove the resulting process from the scope and spirit of the appendedclaims.

Illustrated in the drawing is a particularly preferred reaction zoneconfiguration in which the fresh feed charge stock in line 22 and thevaporous phase from hot separator 8 are processed in a first parallelreactor system 1 and 2, each of which contains two reaction zones. Thesecond parallel reactor system 3 and 4, each of which also contains tworeaction zones, is utilized to further react and convert the liquidphase from hot flash zone 9 in admixture with the total hydrogen recyclestream in line 47. In order to simplify the drawing, only twodirect-fired heaters 5 and 6 are shown, each of which serves one of theparallel reactor systems. As a practical matter, each parallel reactorsystem would include two such heaters each of which would raise thetemperature of the feed to one of the reactors in each parallel system.It will become evident, from the following detailed description, thatthis simplification has no effect upon the illustration.

DETAILED DESCRIPTION OF DRAWING

With specific reference now to the drawing, the technique encompassed bymy inventive concept will be described in conjunction with acommercially-scaled unit designed for a daily feedstock capacity of50,000 barrels (331.3 M³ /hour). The charge stock is a black oil of thetype hereinbefore described, having an average molecular weight of 430,an API gravity of 16.3° and a specific gravity of 7.97 lbs/gal. (951.4Kg/M³). For the remainder of the description of the drawing, includingthe several tables which follow, the quantities of the various processstreams will be expressed as pound moles/hour. Charge stock, in theamount of about 1,624.3 moles/hour, is introduced into the process byway of line 22 at a temperature of about 350° F. (176.7° C.) and apressure of about 2,500 psig. (171.2 atm.); the pressure decreases toabout 2,400 psig. (167.8 atm.) due to normal fluid flow through a hotoil belt (not illustrated) to increase its temperature from thatexisting at the storage facility. The charge stock is admixed with about48,273.86 pound moles/hour of a hydrogen-rich vaporous phase (80.3%) inconduit 23 (derived from hot separator 8), having a temperature of about800° F. (426.7° C.) and a pressure of about 2,400 psig. (164.4 atm.).The resulting mixture, at a temperature of about 596° F. (313.3° C.) andsubstantially the same pressure, continues through line 22 into adirect-fired heater 5.

The heated combined feed is withdrawn from heater 5, via line 24, at atemperature of about 755° F. (401.7° C.) and a pressure approximating2,340 psig. (160.3 atm.). About one-half of the combined feed isdiverted through line 25 into reaction chamber 2, the remaindercontinuing through line 24 into reaction chamber 1. In thisillustration, as aforesaid, each chamber contains two individualreaction zones; from a practical viewpoint, this is advantageous in thatit permits the use of quench streams intermediate the catalyst beds inorder to temper the temperature increase brought about by the exothermicnature of the reactions. Since the quenching technique forms noessential part of the present invention, and is thoroughly described inthe prior art, the same is not illustrated in the drawing. Producteffluent from chamber 1 is recovered via line 26 and admixed with theproduct effluent from reaction chamber 2 in conduit 27; the mixture isat a temperature of about 800° F. (426.7° C.) and a pressure of about2,240 psig. (153.5 atm.). Component analyses of the total combined feedto reactors 1 and 2, and of the total product effluent in line 26, aregiven in the following Table I.

The total reaction product effluent is initially separated in hotseparator 7 at substantially the same pressure and, as previously setforth, at a temperature preferably not exceeding 750° F. (398.9° C.).Therefore, prior to passing the line 26 effluent into hot separator 7, aquench stream obtained via conduit 28 as a liquid phase from warm flashzone 11, is admixed therewith in the amount of about 958.12 moles/hour.

                  TABLE I:                                                        ______________________________________                                        Reactors 1 and 2 Component Analyses                                                          Total        Total                                             Component      Charge       Effluent                                          ______________________________________                                        Water          2084.86      2111.99                                           Hydrogen Sulfide                                                                             196.10       878.52                                            Hydrogen       38764.94     35196.52                                          Methane        5972.51      6033.48                                           Ethane         450.77       485.59                                            Propane        188.12       216.65                                            Butanes        89.99        112.81                                            Pentanes       32.41        45.96                                             Hexanes        20.84        34.62                                             Heptane-400° F.                                                                       99.38        195.17                                            400° F.-650° F.                                                                266.13       456.72                                            650° F.-1050° F.                                                               107.85       1269.93                                           1050° F.-plus                                                                         --           159.16                                            Fresh Feed     1624.30      --                                                ______________________________________                                    

The quench is at a temperature of 180° F. (82.2° C.) and a pressure of2,240 psig. (153.5 atm.), which results in a mixture having atemperature of 750° F. (398.9° C.). Hot separator 7 serves primarily toconcentrate the hydrogen in a vaporous phase in line 29 while producinga liquid phase, rich in 400° F.-plus (204.4° C.) hydrocarbons, in line42. Additionally, the purpose of the hot separator is to concentrate allthe remaining 1050° F.-plus (565.6° C.) hydrocarbons in the liquidphase. Component analyses of the total feed to hot separator 7, thevaporous phase in line 29 and the liquid phase in line 42 are given inthe following Table II.

Vaporous phase components from hot separator 7 are admixed with a secondportion of the warm flash zone liquid, in the amount of 2541.88moles/hour, being diverted through line 30 at a temperature of about180° F. (82.2° C.) and a pressure of about 2240 psig. (153.5 atm.).

                  TABLE II:                                                       ______________________________________                                        Hot Separator (7) Stream Analyses                                                         Total                                                             Component   Charge     Line 29    Line 42                                     ______________________________________                                        Water       2111.99    2111.99    --                                          Hydrogen Sulfide                                                                          899.11     865.75     33.36                                       Hydrogen    35208.89   34234.38   974.51                                      Methane     6049.90    5862.46    187.44                                      Ethane      493.83     463.67     30.16                                       Propane     228.36     213.64     14.73                                       Butanes     128.16     118.38     9.78                                        Pentanes    61.24      55.51      5.73                                        Hexanes     55.36      49.19      6.17                                        Heptane-400° F.                                                                    603.24     501.33     101.91                                      400° F.-650° F.                                                             819.65     363.69     455.96                                      650° F.-1050° F.                                                            1336.31    66.37      1269.94                                     1050° F.-plus                                                                      159.16     --         159.16                                      ______________________________________                                    

The resulting mixture, having a temperature of about 540° F. (282.2°C.), continues through line 29 into condenser 16. Cooled and condensedcomponents, at a temperature of about 130° F. (54.4° C.) and a pressureof about 2200 psig. (150.8 atm.), are introduced by way of conduit 31into cold separator 12. Principal functions of cold separator 12 includeconcentrating hydrogen in the vaporous phase withdrawn via conduit 37,effect substantially complete (98.1%) water removal through line 32 andconcentrate the heavier hydrocarbons in the liquid phase recovered inconduit 33. Cold separator stream analyses are presented in Table III.

                  TABLE III.                                                      ______________________________________                                        Cold Separator Stream Analyses                                                Component   Line 31    Line 37    Line 33                                     ______________________________________                                        Water       2111.99    41.18      --                                          Hydrogen Sulfide                                                                          920.38     704.29     216.08                                      Hydrogen    34267.20   33819.93   447.27                                      Methane     5906.04    5585.03    321.00                                      Ethane      485.52     405.30     80.22                                       Propane     244.72     161.84     82.87                                       Butanes     159.10     71.58      87.52                                       Pentanes    96.05      21.90      74.15                                       Hexanes     104.23     12.09      92.14                                       Heptane-400° F.                                                                    1583.96    17.79      1566.17                                     400° F.-650° F.                                                             1326.57    0.02       1326.55                                     650° F.-1050° F.                                                            242.49     --         242.49                                      1050° F.-plus                                                                      --         --         --                                          ______________________________________                                    

Cold separator liquid components, at a temperature of about 130° F.(54.4° C.), are introduced into heat-exchanger 15 wherein they arecontacted by a suitable heat-exchange medium entering via line 34 andexiting via line 35. The temperature is increased to about 363° F.(183.9° C.), and the liquid components are introduced via line 36 intowarm flash zone 11 at a pressure of about 300 psig. (21.42 atm.). Aspreviously stated in the discussion of the appropriate prior art, warmflash zone 11 is the contradistinction over prior art techniques inwhich cold separator liquid components pass into a cold flash zone. Warmflash zone 11 serves to remove at least about 70.0% of the incomingmethane in the vapor phase withdrawn via line 55; in the presentillustration, methane removal is about 81.3%. Therefore, there exists nonecessity to withdraw a drag stream via line 56 in order to prevent thebuild-up of methane in the above-described separation cycle. About3499.79 moles/hour of warm flash zone liquid in line 28 are introducedinto pump 19, by which the pressure is increased to about 2300 psig.(157.6 atm.). Of this amount, approximately 2541.88 moles/hour arediverted through line 30 to be admixed with the vaporous phase in line29 from hot separator 7. The remainder continues through line 30 toserve as quench for the reaction product effluent in line 26. Warm flashzone 11 stream analyses are given in the following Table IV:

                  TABLE IV:                                                       ______________________________________                                        Warm Flash Zone Stream Analyses                                               Component       Line 55     Line 28                                           ______________________________________                                        Water           --          --                                                Hydrogen Sulfide                                                                              140.87      75.21                                             Hydrogen        402.07      45.20                                             Methane         261.00      60.01                                             Ethane          50.13       30.09                                             Propane         40.09       42.79                                             Butanes         31.45       56.07                                             Pentanes        18.32       55.82                                             Hexanes         6.36        75.78                                             Heptane-400° F.                                                                        75.50       1490.67                                           400° F.-650° F.                                                                 0.88        1325.68                                           650° F.-1050° F.                                                                --          242.48                                            ______________________________________                                    

Liquid phase components in line 42, from hot separator 7, at about 750°F. (398.9° C.) and a pressure of about 2240 psig. (153.5 atm.), areintroduced into hot flash zone 9 at about 745° F. (396.1° C.) and thesignificantly lower pressure of about 245 psig. (17.68 atm.). Theprincipal function of hot flash zone 9 is to recover a vaporous phase,in line 43 having substantially no hydrocarbons boiling above about1050° F. (565.6° C.). This heavier material, representing unconvertedraw oil, and the greater proportion of all the 400° F.-1050° F. (202.4°C.-565.6° C.) normally liquid components are recovered by way of line46. This liquid phase, after being increased in pressure, via pump 18,to about 2500 psig. (171.2 atm.) continues through line 46 as the feedto the second parallel reactor system illustrated as zones 3 and 4.Stream analyses of the liquid and vaporous phases from hot flash zone 9are given in Table V.

                  TABLE V.                                                        ______________________________________                                        Hot Flash (9) Stream Analyses                                                 Component       Line 43     Line 46                                           ______________________________________                                        Water           --          --                                                Hydrogen Sulfide                                                                              30.19       3.18                                              Hydrogen        907.14      67.37                                             Methane         174.03      13.41                                             Ethane          25.40       4.76                                              Propane         12.07       2.65                                              Butanes         7.63        2.16                                              Pentanes        4.17        1.56                                              Hexanes         4.20        1.96                                              Heptane-400° F.                                                                        57.20       44.71                                             400° F.-650° F.                                                                 81.75       374.21                                            650° F.-1050° F.                                                                32.34       1237.60                                           1050° F.-plus                                                                          --          159.16                                            ______________________________________                                    

Vaporous components from hot flash zone 9, in line 43, are admixed withabout 1154.09 moles/hour of a vaporous phase, from a second hot flashzone 10, in line 53; the latter is at a temperature of about 794° F.(423.3° C.). The mixture, at a temperature of about 768° F. (408.9° C.)and a pressure of about 245 psig. (17.34 atm.), continues through line43 into condenser 15 wherein the temperature is decreased to a level ofabout 120° F. (48.9° C.). Condensed material is introduced, via conduit44, into a compressor suction drum 14 at a pressure of about 225 psig.(16.32 atm.). A hydrogen-rich (80.3%) vaporous phase is recoveredthrough line 38, while the condensed material is recovered by way ofconduit 45 and transmitted thereby to suitable product recoveryfacilities. Stream analyses of the suction drum vapor and liquid phases,and the total feed thereto, are presented in Table VI.

                  TABLE VI.                                                       ______________________________________                                        Suction Drum Stream Analyses                                                  Component    Line 44    Line 38    Line 45                                    ______________________________________                                        Water        --         --         --                                         Hydrogen Sulfide                                                                           35.55      33.14      2.41                                       Hydrogen     1752.24    1748.63    3.61                                       Methane      323.06     318.91     4.15                                       Ethane       45.94      43.67      2.27                                       Propane      20.55      17.80      2.75                                       Butanes      12.17      8.60       3.57                                       Pentanes     6.07       2.67       3.38                                       Hexanes      5.58       1.37       4.21                                       Heptane-400° F.                                                                     66.11      1.60       64.51                                      400° F.-650° F.                                                              134.68     --         134.68                                     650° F.-1050° F.                                                             88.26      --         88.26                                      1050° F.-plus                                                                       0.01       --         0.01                                       ______________________________________                                    

Since the reactions being effected are principally exothermic in nature,hydrogen is consumed in the overall process. Therefore, make-up hydrogenis introduced into the process via conduit 41, in the amount of 5939.23moles/hour (97.0% purity), and admixed with the suction drum vapors inline 38. Compressor 21 increases the pressure from a level of about 200psig. (14.61 atm.) to about 2200 psig. (150.8 atm.); the compressedvapors are admixed with the vaporous phase from cold separator 12 inline 37, the mixture continuing through line 38 into the lower end of anamine absorber 13. Lean amine absorbent solution is introduced into theupper end through line 39. Absorber 13 serves to remove hydrogen sulfidefrom the combined hydrogen-rich vapors; the rich amine solution,containing 663.69 moles/hour of hydrogen sulfide, 102.74 moles/hour ofhydrogen and 3.18 moles/hour of methane, is recovered via conduit 40 andtransmitted thereby to a suitable amine absorbent regeneration facility.Component analyses of the total feed to amine absorber 13 and thehydrogen-rich recycle gas in line 47, of reduced hydrogen sulfidecontent, are given in Table VII.

The hydrogen sulfide depleted vapors are recovered from absorber 13, ata temperature of about 160° F. (71.1° C.) and a pressure approximating2195 psig. (150.42 atm.), and continue through line 47 into recycle gascompressor 20, wherein the pressure is increased to about 2610 psig.(178.7 atm.), the temperature increasing to about 190° F. (26.1° C.).Water, in the amount of about 2024.29 moles/hour, is introduced by wayof line 57 at a temperature of 100° F. (37.8° C.).

                  TABLE VII:                                                      ______________________________________                                        Amine Absorber Stream Analyses                                                Component      Total Feed   Line 47                                           ______________________________________                                        Water          41.18        41.18                                             Hydrogen Sulfide                                                                             737.43       73.74                                             Hydrogen       41329.60     41226.85                                          Methane        6082.11      6078.93                                           Ethane         448.98       448.98                                            Propane        179.64       179.64                                            Butanes        80.18        80.18                                             Pentanes       24.58        24.58                                             Hexanes        13.46        13.46                                             Heptane-400°  F.                                                                      19.39        19.39                                             400° F.-650° F.                                                                0.02         0.02                                              650° F.-1050° F.                                                               --           --                                                ______________________________________                                    

The mixture continues through conduit 47 at a pressure of about 2610psig. (178.7 atm.) and a temperature of about 178° F. (81.1° C.), and isintroduced thereby into direct-fired heater 6. The thus-heated material,at a pressure of about 2500 psig. (171.2 atm.) and a temperature ofabout 854° F. (456.7° C.), is withdrawn via line 48 and admixed with theliquid phase, from hot flash zone 9, in line 46. Approximately one-halfof the resulting mixture, which is at a temperature of about 784° F.(417.8° C.), is diverted through conduit 41 into reaction zone 4, theremainder continuing through line 48 into reaction zone 3. Reactionproduct effluent, at about 800° F. (426.7° C.) and a pressure of about2400 psig. (164.4 atm.), is recovered from reactor system 3 via line 50and from reactor system 4 via line 51; these are combined and introducedinto hot separator 8 via conduit 50. Component analyses of the totalfeed to reactor systems 3 and 4, and the total reaction product effluenttherefrom are presented in Table VIII:

                  TABLE VIII:                                                     ______________________________________                                        Reactors 3 and 4 Component Analyses                                                          Total        Total                                             Component      Charge       Effluent                                          ______________________________________                                        Water          2065.47      2084.86                                           Hydrogen Sulfide                                                                             76.92        201.92                                            Hydrogen       41294.22     39665.92                                          Methane        6092.34      6131.52                                           Ethane         453.73       474.64                                            Propane        182.29       198.14                                            Butanes        82.34        95.56                                             Pentanes       26.13        34.86                                             Hexanes        15.42        22.72                                             Heptane-400°  F.                                                                      64.10        113.44                                            400° F.-650° F.                                                                374.23       465.38                                            650° F.-1050° F.                                                               1237.60      1172.92                                           1050° F.-plus                                                                         159.16       150.26                                            ______________________________________                                    

Reaction product effluent is introduced into hot separator 8 at atemperature of about 800° F. (426.7° C.) and a pressure of about 2400psig. (164.4 atm.). A hydrogen-rich vaporous phase is recovered in line23, in the amount of about b 48,273.86 moles/hour, and admixed with theraw oil charge in line 22. The principally liquid phase is recovered vialine 52, and introduced thereby into the second hot flash zone 10 at thereduced pressure of 245 psig. (17.34 atm.) and a temperature of about794° F. (423.3° C.). Hot separator 8 stream analyses are presented inTable IX.

                  TABLE IX:                                                       ______________________________________                                        Hot Separator (8) Stream Analyses                                             Component     Line 23       Line 52                                           ______________________________________                                        Water         2084.86       --                                                Hydrogen Sulfide                                                                            196.10        5.83                                              Hydrogen      38764.94      900.95                                            Methane       5972.51       159.01                                            Ethane        450.77        23.87                                             Propane       188.12        10.02                                             Butanes       89.99         5.58                                              Pentanes      32.41         2.44                                              Hexanes       20.84         1.88                                              Heptane-400°  F.                                                                     99.38         14.06                                             400° F.-650° F.                                                               266.13        199.26                                            650° F.-1050° F.                                                              107.85        1065.07                                           1050° F.-plus                                                                        --            150.25                                            ______________________________________                                    

Hot flash zone 10 liquid components are recovered via conduit 54 andtransmitted thereby to suitable product recovery facilities. Vaporouscomponents withdrawn via conduit 53 are combined with the vaporousphase, from the first hot flash zone 9, in conduit 43, and introducedthereby into condenser 15. Hot flash zone stream analyses are given inTable X.

For the purpose of indicating the overall component yields of the blackoil conversion process above described, only the following streams areconsidered: the rich amine solution in line 40; the suction drum liquidphase in line 45; the liquid phase, in line 54, from the second hotflash zone 10; and, the overhead vaporous phase, in line 55, from warmflash zone 11. Hydrogen consumption is about 5198.76 moles/hour; in thefollowing Table XI, neither water, nor hydrogen is indicated.

                  TABLE X:                                                        ______________________________________                                        Hot Flash Zone (10) Stream Analyses                                           Component       Line 54     Line 53                                           ______________________________________                                        Water           --          --                                                Hydrogen Sulfide                                                                              0.46        5.37                                              Hydrogen        55.86       845.10                                            Methane         9.99        149.02                                            Ethane          3.33        20.54                                             Propane         1.54        8.48                                              Butanes         1.03        4.54                                              Pentanes        0.55        1.89                                              Hexanes         0.50        1.38                                              Heptane-400°  F.                                                                       5.15        8.91                                              400° F.-650° F.                                                                 146.33      52.93                                             650° F.-1050° F.                                                                1009.14     55.92                                             1050° F.-plus                                                                          150.24      0.01                                              ______________________________________                                    

                  TABLE XI:                                                       ______________________________________                                        Overall Process Yields                                                        Component            Moles/Hour                                               ______________________________________                                        Hydrogen Sulfide     807.43                                                   Methane              278.32                                                   Ethane               55.73                                                    Propane              44.38                                                    Butanes              36.05                                                    Pentanes             22.23                                                    Hexanes              21.07                                                    Heptane-400°  F.                                                                            145.16                                                   400° F.-650° F.                                                                      281.89                                                   650° F.-1050° F.                                                                     1097.40                                                  1050° F.-plus 150.25                                                   ______________________________________                                    

The foregoing specification, particularly when read in conjunction withthe illustrative example and the accompanying drawing, clearlyillustrates the method of effecting the process of the present inventionand the benefits afforded through the utilization thereof.

I claim as my invention:
 1. A process for the conversion of a black oilcharge stock, of which at least 10.0% by volume boils above about 1050°F., which process comprises the sequential steps of:(a) reacting saidcharge stock and hydrogen, in a first catalytic reactor system, at atemperature above about 700° F. and a pressure greater than about 1000psig.; (b) separating the resulting first reaction product effluent, ina first separation zone, under substantially the same pressure and atemperature not substantially exceeding 750° F., to provide a firstvaporous phase and a first liquid phase; (c) cooling said first vaporousphase to a temperature in the range of about 50° F. to about 150° F.,and separating the cooled vaporous phase, in a second separation zone atsubstantially the same pressure as said first separation zone, toprovide (i) a hydrogen-rich second vaporous phase and, (ii) amethane-containing second liquid phase; (d) increasing the temperatureof said second liquid phase, and separating the heated liquid phase, ina third separation zone at a substantially reduced pressure, saidtemperature and pressure being selected to provide (i) a third liquidphase and, (ii) a third vaporous phase containing at least about 70.0%of the methane contained in said second liquid phase; (e) admixing afirst portion of said third liquid phase with said first vaporous phaseand a second portion with said first reaction product effluent; (f)separating said first liquid phase at substantially the sametemperature, in a fourth separation zone under a substantially reducedpressure below about 1000 psig., to provide (i) a fourth liquid phaseand, (ii) a fourth vaporous phase; and, (g) further reacting said fourthliquid phase with hydrogen, in a second catalytic reactor system at anincreased pressure above about 1000 psig.
 2. The process of claim 1further characterized in that said fourth liquid phase is reacted insaid second catalytic reactor system at substantially the sametemperature as it emanates from said fourth separation zone.
 3. Theprocess of claim 1 further characterized in that at least a portion ofsaid second vaporous phase is heated to a temperature above about 700°F., and introduced into said second catalytic reactor system.
 4. Theprocess of claim 1 further characterized in that the first portion ofsaid third liquid phase is admixed with said first vaporous phase priorto the cooling thereof.
 5. The process of claim 1 further characterizedin that said second liquid phase is heated to a temperature in the rangeof about 250° F. to about 500° F., and said third separation zone ismaintained under a pressure in the range of about 200 psig. to about 450psig.
 6. The process of claim 1 further characterized in that thereduced pressure in said fourth separation zone is in the range of about100 psig. to about 400 psig.
 7. The process of claim 1 furthercharacterized in that the product effluent from said second catalyticreactor system is separated, in a fifth separation zone, atsubstantially the same pressure and a temperature not substantiallyexceeding 800° F., to provide (i) a fifth vaporous phase and, (ii) afifth liquid phase.
 8. The process of claim 7 further characterized inthat at least a portion of said fifth vaporous phase is admixed withsaid charge stock and introduced therewith into said first catalyticreactor system.
 9. The process of claim 7 further characterized in thatsaid fifth liquid phase is separated at substantially the sametemperature, in a sixth separation zone at a pressure in the range ofabout 100 psig. to about 400 psig.
 10. The process of claim 9 furthercharacterized in that said sixth vaporous phase is admixed with saidfourth vaporous phase, the resulting mixture is cooled to a temperaturein the range of about 50° F. to about 150° F. and introduced into aseventh separation zone at substantially the same pressure to provide(i) a seventh liquid phase and a hydrogen-rich seventh vaporous phase.11. The process of claim 10 further characterized in that at least aportion of said seventh vaporous phase is heated to a temperature aboveabout 700° F. and introduced into said second catalytic reactor system.12. The process of claim 10 further characterized in that (i) saidseventh vaporous phase is admixed with said second vaporous phase, (ii)hydrogen sulfide is removed from the resulting mixture and, (iii) themixture is heated to a temperature above about 700° F. and introducedinto said second catalytic reactor system.